Photointerruptor

ABSTRACT

A light emitting element (1) and a light receiving element (2) are oppositely fixed through a space by an opaque-material package (3) to allow transmission and reception of light therebetween. The light emitting element and the light receiving element have leads which are outwardly extended from a bottom surface (A) of the package (3) and inserted into and soldered to through-holes of a substrate. A movement-preventing bend portion (11g, 21g) having at least a first bend point is formed at a position smaller than a thickness of the substrate from the bottom surface of the package. As a result, where the leads of the photointerrupter are inserted into and soldered to a printed substrate or the like, soldering is possible without causing inclination or positional deviation.

TECHNICAL FIELD

This invention relates to a photointerrupter having a light emittingelement and a light receiving element oppositely placed through a spaceto determine a presence or absence of an object passing through thespace or the like. More specifically, the invention relates to aphotointerrupter having leads provided with a fixing means to preventagainst inclination of fitting in soldering, where the photointerrupteris mounted onto a printed substrate and the leads are soldered thereto.

PRIOR ART

A photointerrupter 10 generally has, as shown in FIGS. 5(a)-(b), a lightemitting element 1 and a light receiving element 2 that are oppositelyplaced with a constant gap and fixed by a package 3 of an opaque moldedresin or case, enabling light transmission and reception. Thephotointerrupter 10 has leads 11, 12 for the light emitting element 1and leads 21, 22 for the light receiving element 2, so that the leads11, 12, 21, 22 are inserted into through-holes 4a of the printedsubstrate 4 and soldered by a flow solder to the printed substrate 4.

The photointerrupter 10 of this kind is arranged to have a space 3boppositely defined by the light emitting element 1 and the lightreceiving element 2 to allow an object to be detected to passtherethrough. When the light emitted from the light emitting element 1is blocked, the light receiving element 2 cannot receive the light. Whenthe object to be detected is not in passing, the light receiving element2 can receive the light emitted by the light emitting element 1. Thus,the object to be detected can be determined of the presence or absencein the opposedly-defined space 3b. However, this opposedly-defined space3b has an interval of as small as several mm or less (e.g. the intervalof the space is approximately 5 mm, where the package has a size ofwidth×thickness (depth)×height of approximately 13.5 mm×5 mm×10 mm).Accordingly, if positional deviation or inclination is present, theobject to be detected cannot pass through the oppositely-defined space3b or the object to be detected is difficult to be accurately detected.For this reason, the mounting of the photointerrupter 10 onto theprinted substrate 4 has to be accurately controlled in height orposition by abutting a bottom surface of the package 3 against theprinted substrate 4 so that the leads can be insert and soldered, by aflow solder, to through-holes formed in the printed substrate 4.

Where the leads of the photointerrupter are inserted and soldered tothrough-holes of a printed substrate as stated above, there may be acase that the photointerrupter is inclined or deviated in position dueto the movement caused by vibrations during transportation in the solderprocess. That is, the photointerrupter is extremely small in size andlight in weight as stated before. Further, the leads of thephotointerrupter is merely inserted into the through-holes of theprinted substrate, wherein the diameter of the through-hole isconsiderably larger (1.3-1.5 times) than the thickness of the lead(diagonal length where rectangular in section). Consequently, ifvibration occurs, the photointerrupter is ready to float up. If thereoccurs floating, inclination or positional deviation during transport,the photointerrupter is soldered at a position as it is, thus beingfixed in a state of inclination or deviation in position. In particular,since the photointerrupter is utilized to detect a presence or absenceof an object to be detected or a change of state by passing the objectto be detected through the gap defined between the light emittingelement and the light receiving element. Accordingly, where there isdeviation (floating or inclination vertical to the printed substrate) inheight or inclination in a horizontal direction even in slight, theobject to be detected becomes difficult to move through an opposedportion between the light emitting element and the light receivingelement, impairing the function as a sensor. In order to avoid this,devising is made such that soldering is performed by placing a weight ona photointerrupter during soldering. However, the fixation is notpositive due to small in size of the photointerrupter, thus raising aproblem of increasing the percentage of unacceptable products due tofloating or the like. The floating or positional deviation of componentsto a printed substrate during solder is not limited to thephotointerrupters and may be encountered in such electric components asresistors, capacitors and ICs. However, the electric parts such asresistors, capacitors and ICs involves no serious problem as to theposition itself provided that the lead can be placed in positiveelectrical contact by solder or the like. Although in such a componentdevising is made as to positioning due to limitation in height orproviding self-standability by corrugating the lead as shown in JapaneseLaying-Open Utility Model Publication No. S57-22270, there is almost nocase of raising problem in slightly floating or deviation in position.

The present invention has been made in order to solve the above-statedproblem, and it is an object to provide a photointerrupter with whichsoldering can be made by inserting a leads of the photointerrupter to asubstrate without causing floating in a direction vertical to thesubstrate or requiring an additional complicated manufacture processsuch as working the leads after being inserted into a through-hole.

It is another object of the present invention to provide aphotointerrupter which can be soldered without incurring inclination ina horizontal direction when the lead of the photointerrupter is solderedto a printed substrate or the like.

DISCLOSURE OF THE INVENTION

A photointerrupter according to the present invention, comprising: alight emitting element having a lead; a light receiving element having alead; a package for oppositely fixing the light emitting element and thelight receiving element through a space so that light transmission andreception can be made therebetween, and having a bottom surface fromwhich the leads outwardly extend; and a float preventing bend portionhaving at least a first bend point formed in the leads extending fromthe bottom surface of the package at a dimensional position smaller thana thickness of the substrate to which the lead from the bottom surfaceis inserted into and fixed to a through-hole.

With this structure, the package at its bottom surface is closelycontacted with a substrate such as the printed substrate. Due to thebend portion of the lead, floating is prevented and vertical movement iscompletely suppressed. As a result, floating or inclination does notoccur during soldering or the like. For a photointerrupter requiringextremely exact positional accuracy, soldering can be made in accurateposition and direction by a simple method without requiring a weight orthe like.

If the bend portion is structured to further have a second bend point ata dimensional position greater than the thickness of the substrate fromthe bottom surface of the package, the second bend point is insertedtoward a back side of the substrate by the springiness of the lead. Thesubstrate is clamped by the bottom surface of the package and the secondbend point portion of the lead, being further firmly fixed.Specifically, the first bend point is provided in the vicinity of acentral axis of the leads extending from the light emitting element andthe light receiving element, and the second bend point is provided at aposition greater than a radius of the through-hole of the substrate fromthe central axis. Or otherwise, the first bend point is provided at aposition that contacts with an inner wall of the through-hole when thelead is inserted into the through-hole, and the second bend point isprovided at a position that is outward of the inner wall of thethrough-hole when the lead is inserted into the through-hole.Incidentally, if the vertical (radial) position of the second bend pointto a lead axis (a central axis of the lead), when an external force isapplied, the second bend point passes through the through-hole to theback side of the substrate.

The bend portion may have further a second bend point at a dimensionalposition smaller than the thickness of the substrate from the bottomsurface of the package, and the first and second bend points are eachformed contactable with the inner wall of the throughhole. With such astructure, the first bend point and the second bend point are contactedwith inner walls of the through-holes, and firmly fixed with the bottomsurface of the package without movement due to vibration or the like. Athird bend point may be further provided at a dimensional positionsmaller than the thickness of the substrate from the bottom surface ofthe package. If the third bend point is formed abutable against theinner wall of the through-hole, further firm fixing is provided.

A projection (small in clearance) that can be fitted to a fitting holeformed in the substrate may be provided on the bottom surface of thepackage. This enables the positioning in a horizontal direction to bepositively made even if a clearance between the lead and thethrough-hole is large. The projection may be provided two or more atasymmetric locations with respect to a center point on the bottomsurface of the package. This structure is preferred because, when thephotointerrupter is reversed in direction, the projection will not fitin the fitting hole, eliminating the possibility of soldering in reversedirection.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1(a) to 1(c) are a side view of one example of a photointerrupterof the present invention, an explanatory view showing a relationshipbetween a through-hole of a substrate and a lead when mounted on thesubstrate such as a printed substrate, and a bottom view;

FIG. 2 is an explanatory view showing another form example of a bendportion of the lead of the photointerrupter of the present invention;

FIG. 3 is an explanatory view showing another form example of a bendportion of the lead of the photointerrupter of the present invention;

FIG. 4 is an explanatory view showing a further form example of a bendportion of the lead of the photointerrupter of the present invention;

FIGS. 5(a) to 5(b) are explanatory views to mount a conventionalphotointerrupter onto a substrate.

BEST FORM FOR PRACTICING THE INVENTION

The photointerrupter of the invention will now be explained withreference to the drawings.

A photointerrupter 10 of the invention, as shown in FIG. 1(a), has anopposed light emitting element 1 and light receiving element 2 to allowtransmission and reception of light therebetween, wherein they are fixedby an opaque material case or molding-resin package 3 formed of anopaque material for a wavelength of the light to be received by thelight receiving element 2, preventing an external light from intrudingtherein. The package 3 covers separately the light emitting element 1and the light receiving element 2, except for light transmitting andreceiving portions for the light emitting element 1 and the lightreceiving element 2, thereby providing a space 3b at a opposed portionof them. The light emitting element 1 and the light receiving element 2respectively have leads 11, 21 so that the leads 11, 21 extends from abottom surface of the package 3 to the outside. The photointerrupter 10of the present invention is characterized in that these leads 11, 12each have, at a portion extending outward from the bottom surface of thepackage 3, a float-preventing bend portion 11g, 12g having at least afirst bend point 11a formed at a position that is smaller than athickness of a substrate through which the lead is fixed by beinginserted into a through-hole. Incidentally, although the light emittingelement 1 and the light receiving element 2 each have two leads 11, 12,21, 22 extending therefrom as shown in a bottom view in FIG. 1(c), thetwo leads are respectively formed with bend portions in a same form asviewed from a side thereof. They are overlappingly seen in the side viewshown in FIG. 1(a). Incidentally, in FIG. 1(a) and FIG. 1(c), 31, 32 arefirst and second projections for preventing positional deviation due torotation in a horizontal direction.

The bend portions 11g, 21g of the leads 11, 21 are formed in such apositional relationship, for example, as to a through hole 4a and a lead11 as shown in FIG. 1(b), wherein the lead 11 is inserted into thethrough-hole 4a of the substrate 4 and the photointerrupter is mountedon the substrate 4. That is, the lead 11 extends straight from a lightemitting portion of the light emitting element 1 (the center of lead 11in this direction is hereinafter referred to as a lead central axis).The lead is bent in a direction away from a central axis of the lead 11at a first bend point 11a located at a distance h smaller than athickness t of the substrate 4 from a bottom surface A of the package.The lead 11 is then bent toward the central axis side at a second bendpoint 11b located at h₂ that is greater than the thickness t of thesubstrate of the bottom surface A of the package 3, and has a third bendpoint 11c such that it extends along the central axis therefrom. Thefirst to third bend points 11a-11c are formed in the above-statedpositional relationship in a vertical direction relative to thethickness of the substrate 4 attached.

On the other hand, the positional relationship in a direction (radialdirection) rectangular to a central axis direction of extension of theleads 11 is as follows. That is, the first and third bend points 11a,11c are formed in the vicinity of the central axis that the lead 11extends. The second bend point 11b is formed at a position that thedistance d from the central axis to an outer end that the lead 11 isbent is greater than a radius r of the through-hole 4a. Incidentally, ifthis distance d is excessively great, the lead 11 becomes difficult toinsert into the through-hole 4a during mounting a photointerrupter ontothe substrate 4. It is preferred that the distance is approximately 2.5r or the smaller.

As a concrete example, where the photointerrupter having a lead 11 witha thickness of 0.4 mm×0.45 mm, with a rectangular section, is mounted byinsertion to a substrate 4 with a thickness of 1.2 mm or 1.6 mm having athrough-hole 4a having a diameter of approximately 0.8-1 mm, thedistance h₁ of the first bend point 11a from the bottom surface A isgiven of approximately 1 mm and the distance h₂ of the second bend point11b from the bottom surface A is of approximately 2 mm. Also, thedistance d of the second bend point 11b from the central axis to theouter end is given approximately 0.75-0.95 mm.

Projections 31, 32 are provided in order to prevent against positionaldeviation such as rotation in the horizontal direction, as shown in FIG.1(a) and FIG. 1(c), during soldering the leads of the photointerrupter10 to the through-holes 4a. That is, the through-hole 4a of thesubstrate 4 are formed with an allowance of nearly 1.3 times the leadthickness, as stated before, being large in clearance. This is due toconsiderations of easiness in insertion of the lead into thethrough-hole and durability of a mold for the substrate (if adjusted tothe lead thickness, a convex portion of the mold is thinned in thicknessto lose durability). For this reason, the mere insertion of the leadinto the through-hole tends to induce rotation due to chatter. Thestructure mentioned before can cause rotation in horizontal directions,even if the vertical float relative to the substrate is prevented.However, if the projections 31, 32 are provided with the provision offitting holes to reduce chatter and clearance with respect to theprojections for inserting into the fitting holes, the horizontalpositioning in position can be positively carried out. The projections31, 32 are provided in a diameter of approximately 0.7 mm and a heightof 0.7 mm. The fitting holes are formed in a diameter of approximately0.8-0.9 mm, being thicker than the thickness of the lead. The fittingholes on the substrate side are in a same degree as the through-hole,and accordingly there is no possibility of impairing the durability ofthe mold.

The projections 31, 32, even if provided only one in number at thebottom surface, can sufficiently suppress against horizontal inclinationin relation to the other lead. However, if provided two or more, therotation is completely prevented. In this case, it is preferred that thefirst projection 31 is provided at a corner on a diagonal line and thesecond projection 32 is on a side deviated from a corner, as shown in abottom view in FIG. 1(c). Such asymmetrical arrangement (not in a pointsymmetry) with respect to a central point A1 in the bottom surface caneliminate the fear of soldering reverse in position, despite the leads11, 12 and the leads 21, 22 are in the same form.

The photointerrupter 10, shown in FIG. 1(a) to FIG. 1(c), has theabove-stated bend portions 11g, 21g provided in the leads 11, 21 for thelight emitting element 1 and the light receiving element 2. Accordingly,when the photointerrupter 10 is attached to the substrate 4, the secondbend point 11b is not inserted by interfering with the through-hole 4a.However, if a force is applied to push in, the lead 11 is inserted dueto the springiness. When the photointerrupter 10 is inserted to aposition that the bottom surface A is placed in abutment against thesubstrate 4, the second bend point 11b passes through the through-hole4a to go out to a backside of the substrate and the lead 11 returns in adirection along its central axis. At this time, since the outer end ofthe second bend point 11b is at the position that the distance d fromthe central axis is greater than the radius r of the trough-hole 4a asstated before, it goes to a reverse side of the through-hole 4a at abackside of the substrate 4. Consequently, the photointerrupter 10attached to the substrate 4 clamps the substrate 4 by a bottom surface Aof the package 3 and the second bend point 11b of the bend portion 11g,21g of the lead 11, 21. As a result, the photointerrupter 10 becomesimmovable in respective upper and lower directions of the substrate 4,thus being firmly fixed.

FIG. 2 shows another example in form of bend portions 11g, 21g of theleads 11, 21. In this example, the bending direction of the lead 11 atthe first bend point 11a is reverse to FIG. 1, i.e. the bending is madein a direction to which the light emitting element 1 and the lightreceiving element 2 face. The bend portions 11g, 21g each have a bendpoint at a same position, as to both in axial position and radialposition vertical to the axis, as that of the example shown in FIG. 1,wherein the function is also the same. The bending direction of theleads 11, 21 is not limited to these examples, but the bending may bemade in other directions such as toward this or backside of the papersurface. Alternatively, the bending may be in directions different fromthe direction of between the light transmitting element 1 and the lightreceiving element 2. Also, the light emitting element 1 and the lightreceiving element 2 each have two leads respectively bent in directionsdifferent from each other. Further, the bending form is not limited tothe sharp-edged convex shape as illustrated, but may be in other formsuch as a semicircular form.

The example shown in FIG. 3 has a lead 11 bent in the same form as inFIG. 1. In this example, the first and second bend points 11a, 11b areformed at a position that the distance (h₁, h₂) from the bottom surfaceA of the package 3 is smaller than the thickness t of the substrate 4.They are formed such that the second bend point 11b exists within thethrough-hole in a state that the bottom surface A of the package 3 is incontact with the surface of the printed substrate 4. In the exampleshown in FIG. 3, the third bend point 11c is also formed to have adistance h₃ from the bottom surface A smaller than the thickness t ofthe printed substrate 4 such that it exists within the through-hole 4a.The dimension D, that is from an outer surface of the first bend point11a to an outer surface of the second bend point 11b, is providedsomewhat greater than the inner diameter 2 r of the through-hole 4a. Dueto this, the lead 11, when pressed into the through-hole, is firmlyfixed in the through-hole. With this structure, the vertical movement ofthe lead can also be suppressed in a manner similar to the structureshown in FIG. 1. Incidentally, the bending direction of the second bendpoint 11b may be in either direction, similarly to the example shown inFIG. 2. In brief, the bending may be made such that the distance Dbetween the outer surface of the second bend point 11b and the outersurface of the first bend point 11a is somewhat greater than the innerdiameter of the through-hole 4a.

An example shown in FIG. 4 has respective bend portions 11g, 21g formedin a zigzag form in the leads 11, 21 for the light emitting element andthe light receiving element. There are fourth bend points 11d, 21d inthe package 3. The leads extend obliquely from the bottom surface A ofthe package 3 instead of in the central axis direction. The first bendpoints 11a, 21a are provided at such a position that the outerperipheral portion contacts with an inner wall of the through-hole 4awhen the leads 11, 21 are inserted into through-holes 4a. The secondbend points 11b, 21b are provided outward of the inner wall of thethrough-hole 4a. That is, the first bend points 11a, 12a are provided ata position equal to or somewhat greater than the radius of thethrough-hole from the central axis of the lead. The second bend points11b, 21b are provided with greater radial dimensions than that. In thiscase, the distance between the outer end of the second bend point 11b,21b and the central axis of the lead is preferably given approximately2.5 times the radius of the through-hole 4a or the smaller.

The relationship in height direction of the first and second bend points11a, 21a, 11b, 21b from the bottom surface A of the package 3 is thesame as the example shown in FIG. 1. In this example, the bend portionfrom the first bend point 11a, 21a toward the light emitting or lightreceiving portion has only the fourth bend portion 11d, 21d. However,there is no problem if the bend point is provided greater in number. Thefourth bend point 11d, 21d may be exposed on an lower side from thebottom surface A of the package 3, provided that the first and secondbend points 11a, 21a, 11b, 21b are in the relationship as stated before.Such structure is no problem. Also, a further bend point may be providedon a tip side of the lead 11, 21 with respect to the second bend point11b, 21b.

When the photointerrupter 10 structured in FIG. 4 is attached to thesubstrate 4, since the second bend point 11b, 21b in radial position isoutward of the diameter of the through-hole 4a, it is stopped withoutbeing inserted into the through-hole 4a. However, the pressing in,similarly to the FIG. 1 structure, causes passing through thethrough-hole 4a due to the elasticity of the lead 11, 21. The substrate4 is clamped by the bottom surface A of the package 3 and the secondbend point 11b, 21b, thus obtaining fixing. According to this structure,the first bend point 11a, 21a also in contact with the inner wall of thethrough-hole 4a, thereby providing fixing further firmly.

With the zigzag form shown in FIG. 4, if the second bend point 11b, 21bis formed at a position from the bottom surface of the package 3 smallerthan the thickness of the substrate 4 such that it also exists withinthe through-hole 4a and the distance from the central axis of the lead11, 21 to the outer surface of the second bend point is almost equal tothe distance from the central axis to the outer surface of the firstbend point 11a, 21a, two convex portions are contacted with the innerwall of the through-hole to provide fixing due to the spring of thelead. Thus similar effect is obtained.

The lead bend portions for the light emitting element and the lightreceiving portion can be always constantly formed by separatelypress-forming with using dies after forming the light emitting elementand the light receiving element. That is, pellets of a light emittingelement and a light receiving element are mounted on a leadframe. Thelight emitting portion or the light receiving portion and wire-bondedand then molded by a transparent resin. Then leads are cut andthereafter formed by die. The light emitting element and the lightreceiving element thus formed are inserted within a case and fixed, orplaced in a metal die and molded by an opaque resin. Thus, aphotointerrupter is obtained that has a light emitting element and alight receiving element fixed by a package.

According to the present invention, the photointerrupter, requiringexact accuracy in position and direction of attachment to a substrate,can be firmly fixed by the bend portion formed in the lead and a bottomsurface of a package thereof. Accordingly, there is no possibility ofmovement due to vibration or the like during soldering, providingfixation with very accurate positional relationship. Further, it issatisfactory to insert into and press in the lead into the through-holeof the substrate. Accordingly, there is no necessity of bending an endportion of the lead after insertion. Thus, a reliable photointerrupterassembly is obtainable by a very simple assembling process and with highyield. Incidentally, in the case of molding, the lead within the packagemay be completely fixed by a molding resin to the bottom surface of thepackage. However, it is further preferred to provide a certain length ina free state, because the lead springiness can be fully utilized wheninserting the second bend portion into the through-hole.

INDUSTRIAL APPLICABILITY

A photointerrupter of the present invention is built, together withother electric circuits, on a printed substrate or the like, and isusable as a sensor such as for a VTR reel sensor and positionaldetection of a printer printhead.

What is claimed is:
 1. A photointerrupter, comprising:a light emittingelement having a lead; a light receiving element having a lead; apackage for oppositely fixing said light emitting element and said lightreceiving element through a space so that light transmission andreception can be made therebetween, and having a bottom surface fromwhich the leads outwardly extend; and a movement preventing bend portionhaving at least a first bend point formed in said leads extending fromthe bottom surface of said package at a dimensional position smallerthan a thickness of the substrate to which the lead from the bottomsurface is inserted into and fixed to a through-hole.
 2. Aphotointerrupter according to claim 1, wherein said bend portion furtherhas a second bend point at a dimensional position greater than thethickness of said substrate from the bottom surface of the package.
 3. Aphotointerrupter according to claim 1, wherein said bend portion hasfurther a second bend point at a dimensional position smaller than thethickness of said substrate from the bottom surface of said package, andsaid first and second bend points each being formed contactable withsaid inner wall of said through-hole.
 4. A photointerrupter according toclaim 1, wherein a projection that can be fitted to a fitting holeformed in said substrate is provided on the bottom surface of saidpackage.
 5. A photointerrupter according to claim 2, wherein said firstbend point is provided in the vicinity of a central axis of said leadsextending from said light emitting element and said light receivingelement, and said second bend point being provided at a position greaterthan a radius of said through-hole of said substrate from the centralaxis.
 6. A photointerrupter according to claim 2, wherein said firstbend point is provided at a position that contacts with an inner wall ofsaid through-hole when said lead is inserted into said through-hole, andsaid second bend point being provided at a position that is outward ofthe inner wall of said through-hole when said lead is inserted into saidthrough-hole.
 7. A photointerrupter according to claim 3, wherein saidbend portion has further a third bend point at a dimensional positionsmaller than the thickness of said substrate from the bottom surface ofsaid package, and said third bend point being formed contactable withsaid inner wall of said through-hole.
 8. A photointerrupter according toclaim 4, wherein said projection is provided two or more at asymmetriclocations with respect to a center point on the bottom surface of saidpackage.